Some reasons to convert from a 6-volt to a 12-volt system:
- brighter lighting
- improved starting
- modern sound system capability
List of parts needed:
- 12-volt alternator with an internal regulator or a 12-volt generator and matching regulator
- A 12-volt alternator requires a later style fuel pump and push rod
- A 3 piece fan shroud kit
- An alternator or generator stand may be required
If the carburetor’s accelerator pump linkage interferes with the alternator, it is best to flip the linkage upside down while updating to a 34 PICT-3 carburetor. You may also grind out a small piece of the alternator casting or consider installing a carburetor adapter to raise a 28 or 30/31 PICT carburetor.
- 12-volt coil
- 12-volt turn signal flasher relay
- 12-vot choke element
- 12-volt headlight relay
- 12-volt idle cut-off solenoid for the carburetor
- 12-volt bulbs for both exterior and interior
- 12-volt wiper motor or 12-volt armature with the 6-volt motor or use a voltage reducing kit
- 12-volt radio or use a voltage reducing kit
- 12-volt horn, optional
- 12-volt starter, optional
If you keep the original 1200-1300cc engine, you may continue to use the 6-volt starter. Avoid cranking for more than five-ten seconds to prolong the life of both the 6-volt starter and the teeth of the flywheel.
- 12-volt flywheel, optional
If you use a 12-volt starter, use a 12-volt flywheel and Dremmel out the bell housing to fit the larger flywheel. Be sure to reset the endplay to 3-5 thousandths. Grinding the o-ring surface may be required to fit the 6-volt crankshaft.
If you use a 12-volt flywheel, use a 6-12-volt starter bushing. Simply insert the correct size tap into the bushing and tap until the old bushing comes out. Slightly grease the new bushing and tap into place with a large brass or copper punch and a small hammer. You may also consider using a starter from an auto stick. An auto stick starter is self-supporting and does not use a bushing in the bell housing. These starters bolt right in and are more powerful.
- Clutch and pressure plate
Use 1967-1970 clutch parts. A 1971 and later pressure plate does not match up to an early throw out bearing.
- 12-volt generator pulley
- 10×900 or 10×913 generator belt
- Ground strap
- 12-volt battery
For generations, the VW Beetle has been celebrated as a simple and reliable means of transportation for people all over the planet. While the Beetle’s engine displacement steadily grew from 1100cc to nearly 1600cc (and, in turn its power output doubled during the car’s life), the car was never thought of as a “performance car,” at least as it came direct from the factory. Despite its lightweight, the Beetle was always characterized as a “slow” performer. With less than 60 SAE horsepower, its lack of performance is not surprising.
In the 1960’s, however, a few individuals looked beyond the Bug’s meager performance. Individuals such as Dean Lowry, Darrel Vittone and Gene Berg found that the VW’s flat four was extremely accepting of performance modifications. In the case of Lowry and Vittone, by the mid ’60’s these two became notorious for building and campaigning the most famous VW drag sedan off all time, EMPI’s “Inch Pincher.” Though it vaguely resembled the same Beetle that was available at the local VW dealer, eventually the “Inch Pincher” was making FOUR times the stock Beetle’s horsepower, topping 200hp. This was enough to push the car to a quarter mile e/t of less than twelve seconds. The VW had become a serious contender!
The successes of these early drag race VW pioneers led to a cult following of VW fans that were bored with the stock pace of their VW’s. By the 1970’s a huge wave of post-college-age individuals found they could mimic much of what was going on at the drags with their own street cars (especially in Southern California, where the hot rod VW was born). Soon it was common to know someone that knew someone that was driving a very quick VW. Clubs, focusing on such hot-rodded VW’s, sprung up all over So California… each club doing their best to “outgun” the others, with what else? Horsepower. Most serious clubs had a few front running street cars that were running the quarter mile in 13 seconds or less, much to the dismay of those that felt they needed a V8 to go fast. This popularity of speed-tuning the VW, underdog that it was, led to an industry that grew to legendary status.
Still today, over 40 years after those first VW drag sedans made their mark on the history of hot-rodding, people are still on the quest for more “go” from their Bugs. While it is entirely possible (and easier than ever) to build a full-on, screaming 2000cc+, 12 second Bug, most people are after a bit less of an extreme. Even the stock 1600 dual port is a good candidate for performance tuning. There are two basic reasons for this: One is the extremely restrictive intake and carburetion setup of the stock engine (single ports are even worse!) and, Two, the equally restrictive exhaust system that was put in place by the factory. You might ask, “If the carb, intake, and exhaust were SO bad, then why did VW equip the car as such?” The answer is VW was known for building simple and reliable cars, not performance cars. The restrictive manner of these parts was “engineered in” in an effort to keep the power output at a reliable level that would not risk damage to the car. For fuel economy, ease of maintenance, and long life the stock set up was hard to beat.
The very nature of these restrictive systems makes the stock VW so easy to tune for power (that and the somewhat exotic design of the flat four itself and the materials it was built of). Take a stock 1600cc that is in healthy running condition; add dual carburetors, an extractor exhaust and a centrifugal-advance ignition, and your stock 1600cc will be transformed. By doing away with the single and diminutive carburetor (and its strangling, stock intake manifold) and replacing it with (at the very least), two-single-barrel, small carburetors (one for each bank) you can (with tuning) realize a 12-15% increase in horsepower. More importantly, the very character of the engine will blossom. What was a lethargic, unwilling, and asthmatic motor now becomes a sharp, hard-edged, and very enthusiastic power plant. The car becomes much more fun to drive. Add a good tuned extractor exhaust and free flow muffler and the power grows. Both the carburetors and the exhaust are relatively simple “bolt on” modifications that can usually be attacked and successfully installed by anyone with some patience and a good set of metric tools. Tuning the dual carburetors can be a tricky undertaking for the novice, but certainly not impossible. Again, it takes patience, and paying attention to details. Modifications to the camshaft and larger, “ported” cylinder heads would be the next logical steps in the sequence of hot-rodding the stock 1600, and are really, beyond the scope of this short article. Instead, here are some specific suggestions for simple “bolt on” mods….
Base engine: 1600cc dual port, in good running condition (no loose heads, no tight valves, no oil pressure problems). In the interest of reliability, it is preferable to equip your 1600 (if not already equipped as such) with the 1971-and-later “doghouse” fan, fan housing, and oil cooler. These cooling parts were designed by the factory to supply more cooling air to the engine, and keep the oil temperature down.
Suggested Carburetion: Dual 40mm Solex-Kadron carburetors on cast aluminum manifolds (try 55 or 60 idle jet and 135 main jet); dual Dellorto 36mm DRLA (2bbl each carburetor) on cast aluminum manifolds, w/ 30mm venturis (try 50 idle jet and 120 main jet); dual Weber 40IDF (2bbl each carburetor) on cast aluminum manifolds, with 28mm venturis (try 50 idle jet and 120 main jet). Do not go larger than 40mm dual Webers on the stock 1600 or you will lose low and mid range engine response.
Suggested Ignition: Bosch centrifugal advance distributor (if available), model #’s “010,” “019” or “009.” (all three are out of production, and are getting hard to come by, if you can find a good “010”, it is generally referred to as THE BEST). Use a stock Bosch blue coil, stock plug wires and maybe step down a heat range in spark plugs (stock is Bosch W8AC, colder would be W7AC). Gap plugs at .028″
Suggested Exhaust: For best horsepower and fuel mileage, a 4-into-1 “header” cannot be beat. Look for one that will connect to stock heat exchangers and, if running dual carbs, has provisions to “block off” the heat-riser ports at cylinders 2 and 4. Mufflers are really up to your taste. “Quiet Pack” mufflers have long been a favorite and have a great deep tone. “Glasspacks” can be (annoyingly) loud, and despite their “fast” sound, rarely make any more power than the “Quiet Pack.” To preserve your header, it’s best to strip all shipping paint off and give it a good few coats of high temperature “exhaust ” paint or for the ultimate finish and longevity, have it ceramic coated.
And remember, after bolting on your “mods,” it’s now even more important to keep your motor regularly tuned and maintained. By letting services slip… you will be sacrificing the performance you paid for (new parts) and the reliability you should enjoy.
More than anything… HAVE FUN.
In the world of hot-rodded VW engines, few parts create such mystery and hype as the high performance camshaft. In the quest for “the ultimate” in horsepower, engine response, and often, bragging rights, enthusiasts will find themselves losing sleep over the selection of the “right” high performance camshaft for their hot VW. While the science of how the high performance VW cam works can be tricky, the selection process doesn’t have to be. It is generally accepted that the camshaft is the component of the engine that brings all the ingredients together. With either the wrong “ingredients” or the wrong camshaft, the results can be very disappointing. However, if all the parts are selected to work in unison, and are assembled correctly the resulting performance and longevity can exceed most expectations. The “how” of the camshaft will be lightly touched on here, but more so, a guide to deciphering all the numbers and how to use the numbers to make your choice. There are some simple “rules” that should be followed for the best results.
First, here are some definitions to common “camshaft terms”:
“Duration”: period, measured in rotation of crankshaft (degrees) that either intake or exhaust valves are open. Note, this degree measurement is usually discussed and advertised at .050″, which refers to either valve having traveled .050″ of lift before degrees are counted.
“Lift”: Lift has two definitions, and it is important to know the difference between the two. “Valve Lift” is just that… the total distance the valve travels as the cam opens it. This, in a VW motor, is usually a larger figure than “cam lift.” This is due to multiplier factor of most rocker arms (especially the aftermarket, high performance “ratio rockers” which can multiply cam lift by up to 1.6 times. “Cam lift” is the distance the lifter actually travels, in direct contact with the cam lobe. There is no multiplication factor when discussing “cam lift.”
Now for the “rules”…
Rule # 1. Ask yourself “what am I going to use this engine for? Driving everyday and on long trips, any time of the year? Drag racing only? An engine that is in between these two extremes? Maybe a little more driver than racer? Or vice versa?” Be honest with your answer. Erring one way or the other can make or break the out come. Here are some guidelines.
A. Daily driver? Stay at the conservative end of the cam spectrum. Select a cam that uses the stock VW rocker arms (not 1.25 or 1.4 ratio rockers), in an effort to keep valve lift no more than .460″. Running a valve lift more than .460″ in an everyday driven car will result in parts wearing out very quickly and make the engine noisier. The duration selection is going to depend on a few more variable… engine displacement, carburetion, or intake system, and gear ratios/ring and pinion ratios.
– 1600 to 1776cc, stock carburetor, stock gear ratios: Stay under 235 degrees duration @ .050″ (actually best to stay with stock cam at this level!)
– 1600 to 1776cc, dual Kadron or Weber 34ICT or Solex 32mm, stock gear ratios: Use duration of 240-245 degrees @ .050″
– 1600 to 1835cc, dual Weber IDF or Dellorto DRLA, stock gear ratios: Stay under 250 degrees of duration @ .050″
– 1900 to 2300cc, dual Weber IDF or Dellorto DRLA, stock gear ratios: No more than 265 degrees of duration @ .050″
B. Going for a weekend hot rod? Not necessarily a daily driver, but still a VW to be used on the street, and driven on a regular basis? This type of engine has gained popularity in the last 10 to 15 years. While more powerful and lively than the daily driver engine, it is also more likely to need more frequent servicing and in depth maintenance (involving disassembling the top end of engine periodically). These “in between” engines can typically move towards the more aggressive spectrum when it comes to camshafts (often the reason behind the increased power and decreased service life). Engines of this nature can be relied upon, on the street, running about to about .540″ lift at valve if the valve train is designed and assembled to lift this much. With the wrong parts or assembly and this much valve lift, you will be asking for a catastrophe…SOON. Duration can also be moved up but remember, as you add duration, you are making the engine less forgiving and less drivable around town. All of the usable power will become available at a higher rpm. One special note here too… these types of engines will only run best with twin, two-barrel carburetors, like the Weber IDFs or IDAs.
Here are suggested durations (note the durations are listed as @ .050″!):
– 1600 to 1641cc, stock gear ratios: no more than 250 degrees @ .050″
– 1679 to 1776cc, stock gear ratios: 250 to 260 degrees @ .050″
– 1800 to 2300cc, stock gear ratios: 255 to 265 degrees @ .050″
C. Building a drag motor? If that is the case, it is best to talk directly to the engine builder or the cam grinder, or both. A drag only engine will be built with little concern for reliability or longevity. The focus will be maximum horsepower. Therefore, both valve lift and duration are going to be much greater when looking for a suitable drag race camshaft. Typically the VW cylinder head can accommodate about .600″ valve lift before extreme measures are taken (machine work to valve spring pockets to accept larger valve springs). This much lift can only be achieved with higher ratio rockers. To figure the lift you want to run, calculate approx 35% of your intake valve diameter inches. The result is approximately the lift you will aim for in a drag engine. To calculate approximate duration you should run (@ .050″), divide engine cc by 4, and then divide that result by 1.77. The result is approximately the duration @ .050″ suggested for a drag race engine. Again, these are approximations.
Rule # 2. Is the engine using stock 69mm stroke crank or a longer “stroker” crankshaft? If the engine is being built around a stock 69mm stroke crank, then it is advisable to err on the conservative side of the duration figures above. If you are planning your project around a longer, “stroker” crank, then you can increase duration accordingly, to the larger figures shown above. The longer stroke crank does more for increasing torque at lower and mid-rpms than any other part of the engine. The effects of increasing duration (weakening lower and mid rpm torque) are usually offset by increasing crank stroke. This means you can literally have the best of both worlds… gutsy bottom end torque, and searing top end horsepower! Engines with similar displacements, but different stroke crank sizes will need different durations. For example, a 1914cc engine is built around 94mm cylinders and a stock 69mm crankshaft, however a slightly smaller cc engine, a 1904cc, is built around 90.5mm cylinders and a 74mm crankshaft. The 1904cc can be tuned for drivability easier than the 1914cc, even with a wilder cam (all other variables being equal; i.e. cylinder head porting, valve diameter, carburetion, compression ratio, etc). So where the 1914cc beings to bottom end torque at about 255 degrees @ .050″, the 1907cc could keep a healthy and wide torque curve with about 262 degrees @ .050″. Crank stroke length and cam timing go hand in hand.
Rule # 3. What type of carburetion will be used on your engine? Carburetion, more than any other factor, can make or break your cam selection. The effect the correct or incorrect carburetion has on how your motor behaves (or misbehaves) cannot be overlooked! An engine setup with a “wild’ cam does not have to be cursed with the stereotypical rough idle and poor off-idle response. This is where the correct choice of carburetion comes into play. For the longest time in the high performance realm (of all cars, not just VWs) the ultimate in carburetion has been one carb throat per cylinder. This type of carburetion is better known as the independent runner system or IR for short. The reason it has been held in such high esteem for so long is that the IR system is a “does it all” system. While it may be obvious that a carb throat per cylinder appears to be the best solution for upper rpm horsepower, it is also the ultimate for a smooth idle, excellent fuel economy and a wide and full torque curve. The IR setup is especially well suited to VW engines running a longer duration camshaft. With that said, regardless of displacement, if you plan on running a camshaft with 245 degrees or more (@.050″) then for best all around performance, you should plan on running twin, two-barrel carburetors. Once you exceed about 252 degrees, the IR carburetor setup is necessary for the street.